1. Field of the Invention
The present invention generally relates to systems and methods for controlling room lighting where an occupancy sensor controls room lighting using standard infrared and/or motion sensor techniques. More particularly, the present invention relates to lighting systems and methods for controlling lighting in an area based on occupancy detection, where 3-way light circuit is employed and at least one of the switches in the 3-way light circuit includes an occupancy sensor.
2. Discussion of the Background
Conventional light management systems where an occupancy sensor is incorporated into a switch of a 3-way light control circuit have been described and implemented utilizing light switches provided by various manufacturers.
For example, one of the conventional light switches that can be implemented in a 3-way light control circuit is shown in FIGS. 1A and 1B. The switch WR 1, which incorporates an occupancy sensor therein, includes ground terminal GR 2, common terminal COM 3 and traveler terminals L1 4 and L2 5. FIG. 1A shows connections for the switch WR 1 in a single pole configuration where the terminal L2 5 is not used, and instead terminal L1 4 is connected to the load 6. On the other hand, as shown in FIG. 1B, in a 3-way light circuit configuration, where two switches WR 1 and WR 10 each incorporating an occupancy sensor are used, travel terminals L1 4 and L2 5 of the first switch WR 1 are connected to travel terminals L2 15 and L1 14 of the second switch WR 10, respectively. As further shown in FIG. 1B, common terminal of the switch WR 1 is connected to the load 6, while the common terminal of the switch WR 10 is connected to the line-hot. When implementing switch WR 1 in a 3-way light circuit, three way operation is only recommended for applications with two such switches, as shown in FIG. 1B. If only WR 1 is used in a 3-way lighting circuit with a standard toggle switch (that does not incorporate an occupancy sensor), the toggle switch must always be turned on for the WR 1 to operate. See “WR-100 Residential Motion Wall Switch”, Installation Instructions, The Watt Stopper, Santa Clara, CA 95050 (2001).
Another conventional light switch which incorporates an occupancy sensor can be used in 3-way circuit with a standard toggle switch as shown in FIG. 2. In this configuration, a standard switch 20 which includes a traveler terminals 25 and 24, a common terminal 23 and ground terminal 22 is used. Switch 30, which incorporates an occupancy sensor, and is connected at terminal 34 of switch 20 by traveler A which is connected to the line-hot by means of jumper 26 to provide constant power to switch 30, and at terminal 35 by traveler B which is connected to the traveler terminal 25 of switch 20, and may be used to provide an indication of the on or off position of the switch 20. Output terminal 33 of switch 30 is connected to the load 36, and the ground terminal 32 is grounded in a conventional manner. See “Wiring Diagram”, http ://www.levitonhelpdesk.com/catalog/images/wdpr180. gif (downloaded Nov. 21, 2006). In the circuit as shown in FIG. 2, true 3-way circuit operation may not be achievable, may require, at the very least providing jumper 26, or may require complex processing to determine the on/off state of the load.
Accordingly, none of the conventional implementations provide 3-way switch incorporating an occupancy sensor that can be used with a convention toggle switch, or with the like 3-way switch incorporating an occupancy sensor, to provide a true 3-way light circuit that can be installed in a pre-wired 3-way light circuit without any wiring modification or extra wiring requirements.